Practice question

Given: A solution contains 10 mL of ethanol ( C₂H₅OH ) and 90 mL of water, with a total volume of 95 mL. What is the volume percentage of ethanol? (Density of ethanol = 0.789 g/mL) These values define the system as per NCERT data. Formula: Volume % = fracVolume of ethanolTotal volume × 100. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Given volume of ethanol = 10 mL, total volume = 95 mL. Volume % = 10/95 × 100 = 10.53% . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.